Frangible disc

There are numerous types of pressure relieving devices available, which include relief valves, safety valves, rupture or frangible disc and blow out hatches or panels. 

Frangible Disc A safety release device that will burst at a predetermined pressure. 

Another method is also employed to prevent loss of the contents of the reactor. A safety valve, placed after the rupture disc, is set to open about 50 psi below the bursting point of the frangible disc. Thus, a rupture of the diaphragm is.sure to be followed by the op ng of the relief valve which has been protected from the corrosive vapors of the autoclave. It is usually feasible to complete the run and then replace the disc and overhaul the safety valve. 

Note DOT and CTC specification 3A and 3AA steel cylinders having a plus rating ( + after the most recent retest date) that have a frangible disc-type pressure relief device may be filled to 110 percent of the marked service pressure when filled with an atmospheric gas. 

Cylinders are typically protected from over-pressurization by frangible gold-plated discs and fusible plugs. 

Burst Diqphragm or Burst Disc(Blowout Diaphragm or Rupture Disc). A flat circular sheet of frangible material (plastic or metal) installed across the pipe suppling liquid propellant to the thrust chamber of a rocket. The purpose of the disc is to prevent flow of liquid until proplnt pressure builds to a preselected value. The disc then shears open and the proplnt is released to flow... 

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